| /* |
| ** Copyright (C) 2002-2011 Erik de Castro Lopo <erikd@mega-nerd.com> |
| ** |
| ** This program is free software; you can redistribute it and/or modify |
| ** it under the terms of the GNU General Public License as published by |
| ** the Free Software Foundation; either version 2 of the License, or |
| ** (at your option) any later version. |
| ** |
| ** This program is distributed in the hope that it will be useful, |
| ** but WITHOUT ANY WARRANTY; without even the implied warranty of |
| ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| ** GNU General Public License for more details. |
| ** |
| ** You should have received a copy of the GNU General Public License |
| ** along with this program; if not, write to the Free Software |
| ** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
| */ |
| |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <math.h> |
| |
| #include "dft_cmp.h" |
| #include "utils.h" |
| |
| #ifndef M_PI |
| #define M_PI 3.14159265358979323846264338 |
| #endif |
| |
| #define DFT_SPEC_LENGTH (DFT_DATA_LENGTH / 2) |
| |
| static void dft_magnitude (const double *data, double *spectrum) ; |
| static double calc_max_spectral_difference (const double *spec1, const double *spec2) ; |
| |
| /*-------------------------------------------------------------------------------- |
| ** Public functions. |
| */ |
| |
| double |
| dft_cmp_float (int linenum, const float *in_data, const float *test_data, int len, double target_snr, int allow_exit) |
| { static double orig [DFT_DATA_LENGTH] ; |
| static double test [DFT_DATA_LENGTH] ; |
| unsigned k ; |
| |
| if (len != DFT_DATA_LENGTH) |
| { printf ("Error (line %d) : dft_cmp_float : Bad input array length.\n", linenum) ; |
| return 1 ; |
| } ; |
| |
| for (k = 0 ; k < ARRAY_LEN (orig) ; k++) |
| { test [k] = test_data [k] ; |
| orig [k] = in_data [k] ; |
| } ; |
| |
| return dft_cmp_double (linenum, orig, test, len, target_snr, allow_exit) ; |
| } /* dft_cmp_float */ |
| |
| double |
| dft_cmp_double (int linenum, const double *orig, const double *test, int len, double target_snr, int allow_exit) |
| { static double orig_spec [DFT_SPEC_LENGTH] ; |
| static double test_spec [DFT_SPEC_LENGTH] ; |
| double snr ; |
| |
| if (! orig || ! test) |
| { printf ("Error (line %d) : dft_cmp_double : Bad input arrays.\n", linenum) ; |
| return 1 ; |
| } ; |
| |
| if (len != DFT_DATA_LENGTH) |
| { printf ("Error (line %d) : dft_cmp_double : Bad input array length.\n", linenum) ; |
| return 1 ; |
| } ; |
| |
| dft_magnitude (orig, orig_spec) ; |
| dft_magnitude (test, test_spec) ; |
| |
| snr = calc_max_spectral_difference (orig_spec, test_spec) ; |
| |
| if (snr > target_snr) |
| { printf ("\n\nLine %d: Actual SNR (% 4.1f) > target SNR (% 4.1f).\n\n", linenum, snr, target_snr) ; |
| oct_save_double (orig, test, len) ; |
| if (allow_exit) |
| exit (1) ; |
| } ; |
| |
| if (snr < -500.0) |
| snr = -500.0 ; |
| |
| return snr ; |
| } /* dft_cmp_double */ |
| |
| /*-------------------------------------------------------------------------------- |
| ** Quick dirty calculation of magnitude spectrum for real valued data using |
| ** Discrete Fourier Transform. Since the data is real, the DFT is only |
| ** calculated for positive frequencies. |
| */ |
| |
| static void |
| dft_magnitude (const double *data, double *spectrum) |
| { static double cos_angle [DFT_DATA_LENGTH] = { 0.0 } ; |
| static double sin_angle [DFT_DATA_LENGTH] ; |
| |
| double real_part, imag_part ; |
| int k, n ; |
| |
| /* If sine and cosine tables haven't been initialised, do so. */ |
| if (cos_angle [0] == 0.0) |
| for (n = 0 ; n < DFT_DATA_LENGTH ; n++) |
| { cos_angle [n] = cos (2.0 * M_PI * n / DFT_DATA_LENGTH) ; |
| sin_angle [n] = -1.0 * sin (2.0 * M_PI * n / DFT_DATA_LENGTH) ; |
| } ; |
| |
| /* DFT proper. Since the data is real, only generate a half spectrum. */ |
| for (k = 1 ; k < DFT_SPEC_LENGTH ; k++) |
| { real_part = 0.0 ; |
| imag_part = 0.0 ; |
| |
| for (n = 0 ; n < DFT_DATA_LENGTH ; n++) |
| { real_part += data [n] * cos_angle [(k * n) % DFT_DATA_LENGTH] ; |
| imag_part += data [n] * sin_angle [(k * n) % DFT_DATA_LENGTH] ; |
| } ; |
| |
| spectrum [k] = sqrt (real_part * real_part + imag_part * imag_part) ; |
| } ; |
| |
| spectrum [k] = 0.0 ; |
| |
| spectrum [0] = spectrum [1] = spectrum [2] = spectrum [3] = spectrum [4] = 0.0 ; |
| |
| return ; |
| } /* dft_magnitude */ |
| |
| static double |
| calc_max_spectral_difference (const double *orig, const double *test) |
| { double orig_max = 0.0, max_diff = 0.0 ; |
| int k ; |
| |
| for (k = 0 ; k < DFT_SPEC_LENGTH ; k++) |
| { if (orig_max < orig [k]) |
| orig_max = orig [k] ; |
| if (max_diff < fabs (orig [k] - test [k])) |
| max_diff = fabs (orig [k] - test [k]) ; |
| } ; |
| |
| if (max_diff < 1e-25) |
| return -500.0 ; |
| |
| return 20.0 * log10 (max_diff / orig_max) ; |
| } /* calc_max_spectral_difference */ |